The present invention is directed to an aerated frozen products, including, but not limited to, ice cream, water ice, frozen yogurt, etc., and the methods for preparing the aerated frozen products.
Traditionally, molded aerated frozen bars, ice cream, or water ice are manufactured by partially freezing an ice cream mix, ice milk mix, frozen yogurt mix, water ice mix, or fruit juice mix in conventional batch or continuous freezers followed by pumping and filling the mix into molds of different shapes and sizes. During the last decade, a new generation of freezers has been developed which are equipped with pre-whippers that enable the mix to be pre-aerated before being partially frozen in the freezer. The molded products are usually quiescently frozen using a cold brine system at xe2x88x9230xc2x0 C. to xe2x88x9240xc2x0 C. If desired, after demolding, the molded products may be coated with chocolate or compound coating. Finally, the products are usually packaged and stored at about xe2x88x9230xc2x0 C. until transport and distribution.
This traditional process for manufacturing molded aerated frozen bars, ice milk, yogurt, ice cream, or water ice has limitations. For example, the partial freezing of the mix in the freezer, followed by quiescent freezing in the molds, leads to the formation of an icy texture, loss of air, and formation of large air cells in the product having a size range of about 110-185 microns (Arbuckle, W. S. Ice Cream, Fourth Edition, 1986, Van Nostrand Reinhold, New York, p 234). Shrinkage of the products is often a problem and when eating the product, a very cold feeling in the mouth is experienced. Furthermore, it is difficult to achieve more than 20% overrun in water ice, a typical overrun is from 0% to 20% and usually is about 5%. It is very difficult to achieve more than 80% overrun and almost impossible to achieve an overrun of 120% or higher in finished ice cream products using conventional manufacturing.
Non molded products have similar problems. Air cells and ice crystals start growing immediately after production of non molded products. Significant air cell and ice crystal growth occurs during transportation, storage at the grocery store or during transportation and storage of the products by the consumer. None of the available non molded ice cream or water ice products inhibit or delay air cell or ice crystal growth after production or during hardening, transportation, or distribution.
Currently, there is no process that can produce very stable finely aerated frozen ice cream, ice milk, yogurt, or water ice having an average air cell size of less than 50 microns and an average ice crystal size of 25 microns or that are heat shock resistant for a period of time after production. Thus, there is a need for finely aerated ice cream, ice milk, yogurt or water ice that maintain a smooth texture, do not suffer from shrinkage, do not give a very cold feeling in the mouth, have an uniform appearance without large air pockets on the surface and have a significantly higher heat shock resistance. Moreover, no process can produce a stable overrun of more than 20% to about 100% for water ice products or an overrun between about 20% to about 250% for ice cream products. The present invention provides products and processes which overcome these disadvantages.
The present invention relates to a process for the production of aerated frozen products comprising the steps of preparing a mixture of ingredients suitable for preparing a aerated frozen product, adding an emulsifier or mixture thereof in a suitable amount to obtain a mix, aerating the mix to obtain an aerated mix having an overrun of about 20% to about 250% for ice cream products and an overrun of about 5% to about 100% for water ice products, and freezing the aerated mix to form the aerated frozen product. In this process, the mix can be an ice cream mix, a water ice mix, a fruit juice mix, a frozen yogurt mix, a sherbet mix, or a mixture thereof.
The emulsifier mixture comprises at least one emulsifier capable of facilitating the formation and stabilization of fat xcex1-crystals and present in an amount of about 0.01% to about 3% by weight of the mix. The emulsifier can be at least one of propylene glycol monostearate, sorbitan tristearate, lactylated monoglycerides, acetylated monoglycerides, or unsaturated monoglycerides, preferably the emulsifier mixture comprises propylene glycol monostearate, sorbitan tristearate, and unsaturated monoglycerides.
The mix of ingredients is typically prepared using conventional methods such as by combining the ingredients with shear mixing to disperse and solubilize them into a homogeneous mass, followed by homogenizing the mass and pasteurizing the homogenized mass. The homogenizing step can be conducted in a two stage homogenizer at a pressure of about 70 bar to about 250 bar in the first stage and of about 0 bar to about 50 bar in the second stage. Also, the mix can be aged after pasteurization by storing at a temperature of about 0xc2x0 C. to about 6xc2x0 C. for about 1 hour to about 24 hours. If desired, the mix can be colored and flavored before being aerated at a temperature of about 0xc2x0 C. to about 12xc2x0 C. to obtain the desired overrun. Preferably, the aerated mix is directly fed to a container or mold and frozen to produce the aerated frozen product, with the freezing being allowed to take place quiescently at a temperature of about xe2x88x9225xc2x0 C. to about xe2x88x9245xc2x0 C.
The aerating step can be conducted by allowing the mix pass through a conventional freezer at a temperature of about xe2x88x924xc2x0 C. to about xe2x88x927xc2x0 C. In contrast, for molded products, the aerating step can be a whipping step conducted by using a conventional mixer at a speed of about 150 rpm to about 1000 rpm and at a flow rate of about 10 L/h to about 1000 L/h.
The invention also relates to an aerated frozen ice cream or water ice which comprises a mixture of ingredients suitable for frozen aerated ice cream or water ice and at least one emulsifier for facilitating formation and stabilization of fat xcex1-crystals.
The aerated frozen ice cream or water ice have an overrun of about 20% to about 250% and of about 5% to about 100%, respectively, and contain air cells having an average size of less than about 50 microns which cells are uniformly distributed throughout the ice cream or water ice and which are substantially invisible to the naked eye. Preferably, the aerated frozen products have air cells with an average size of about 15 microns to about 40 microns and an ice crystal size of less than about 30 microns. The process produces an aerated frozen product having a smooth texture similar to an extruded ice cream and heat shock resistant such that the apparent change in product volume after heat shock treatment is less than about 5% by volume.
If desired, the aerated frozen products can contain inclusions or have a coating that optionally contains inclusions, which are added before or during freezing. Further, the aerated frozen products may be in shell and core products with ice cream as a core and water ice, fruit juice, fruit ice, real fruit, or a mixture thereof as a shell or coating. The latter having an overrun of about 0% to about 20%.